LiT #6 | 250

"Calling someone "250" means they are stupid, as in someone who does something rashly without clearly thinking through it, says Liao, and the phrase can be used as a noun or an adjective.

Some people think the origin of the phrase relates to an ancient Chinese unit of currency called a diao (弔). The Chinese scholars, being modest and humble, would call themselves 二百五, which is a quarter of a diao"

Thanks businessinsider! (NB: I don't think of Sloths as Stupid or Lazy)